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Full text of "The manufacture and properties of iron and steel"

506                                     THE IRON INDUSTRY.
about 40 per cent, of iron. The fuel consumption in the kiln, is about 80 pounds of small coal per ton of ore. The figures quoted give 41.84 per cent, of iron and 13.66 per cent, of silica, but I believe that the figures are rather roseate and refer to the best records rather than to the average, and that the general run of ore after calcining will carry only 40 per cent, of iron with silica up to 19 per cent. The average selling price from 1870 to 1883 is given by Bell as $1.02 per ton at the mines, with 30 cents freight, making a total of $1.32 per ton at the furnace. The value in 1899 is given in the Home Office Reports at $1.01 per ton at the mine. Counting a short haul and the cost of calcining, it can hardly be less than $1.15 per ton for a 30 per cent, ore; this is 3.83 cents per unit, and if the Cleveland pig contains 92 per cent, of iron, the cost of the ore per ton of pig will be $3.52. KirchhofE gives the cost at the furnaces of Bolckow, Vaughan as 85 cents per ton, to which must be added the cost of calcining. For a 30 per cent, ore this means about $3 per ton of pig-iron. The distance from South Durham to Middlesbrough is from 20 to 30 miles, and the freight 50 cents per ton.
The coal from Durham varies, but the coals are often mixed. The average of four samples quoted by Bell is as follows:
Per cent.
C......................................    80.51
H......................................      4.49
O+N....................................      8.03
S..........................'............      1.26
Ash....................................      5.16
Water..................................      1.01
100.46
The fixed carbon was 70.32 per cent, and the loss in coking is over 40 per cent, in beehive ovens. The greater quantity of Durham coke is made in this type of oven, although works in Middlesbrough-are introducing the by-product process. Bell states that the coke runs 6.60 per cent, in ash and 0.96 per cent, in sulphur. KirchhofE gives the composition of four samples, averaging as follows:
Per cent.
Carbon.................................     88.16
Sulphur................................      1.11
Ash....................................       9.33
Water..............,...................      1.40
100.00